The present invention relates to a dual polarization active microwave reflector with electronic scanning, capable of being illuminated by a microwave source in order to form an antenna.
It is known to produce antennas comprising an active microwave reflector. The latter, also called a xe2x80x9creflect arrayxe2x80x9d, is an array of phase shifters which can be controlled electronically. This array lies in a plane and comprises an array of elements with phase control, or a phased array, placed in front of the reflecting means, consisting, for example, of a metal ground plane forming a ground plane. The reflecting array especially comprises elementary cells each one producing reflection and phase shifting, variable by electronic control, of the microwave that it receives. An antenna of this sort provides considerable beam agility. A primary source, for example a horn, placed in front of the reflecting array emits microwaves toward the latter.
One aim of the invention is especially to make it possible to produce an electronic scanning antenna using an active reflecting array and operating with two independent polarizations. To this end, the subject of the invention is an active microwave reflector, capable of receiving an electromagnetic wave, comprising two imbricated waveguide arrays. The bottom of each guide is closed by a circuit carrying out the reflection and the phase shifting of the wave that it receives, one array being designed to receive one polarization and the other array being designed to receive a polarization perpendicular to the previous one.
One embodiment may be such that:
a first array comprises several sets of aligned guides, one row lying in a direction Ox and the set of rows lying in a perpendicular direction Oy, for the same row, the centers C of two consecutive guides being separated by a distance d, two consecutive rows being separated by a distance h, along Oy, and offset one with respect to the other by the distance d/2, along Ox;
the second array comprises several sets of guides aligned in the same way as in the first array, the rows being offset by an angle of 90xc2x0 with respect to those of the first array;
a guide of one array is contiguous only with guides of the other array.
The subject of the invention is also an electronic scanning antenna comprising a reflector as defined above. This antenna may, for example, be of the xe2x80x9cReflect Arrayxe2x80x9d type or of the Cassegrain type.
The particular advantages of the invention are that it makes it possible to obtain a compact, low-weight reflector, that it is simple to use and that it is economical.